Good to see that someone mentioned my favorite German developer Daedalic Entertainment (but I doubt that their games can be called commercially successful or the main source for the point and click genre; Daedalic is a small company and I don't think any of their games sold 100.000 copies or more worldwide).
The biggest German developers in terms of retail sales - Blue Byte (The Settlers, Anno co-developer) and Related Design (Anno main developer afaik) - are both owned by Ubisoft. New entries to the franchises Settlers and Anno usually sell several 100.000 copies in the German speaking area alone.
German game developers and publishers seem to be quite successful,these days in an area that's rarely mentioned on VGC: browser games.
This statistic claims to list the world's most successful browser game developers (I doubt it's complete - where are the Asian developers? - but anyway, it at least shows where German developers really succeed these days): http://www.mmofacts.com/top/browser-mmos/developers
The top 6 on this list are German companies afaik, Blue Byte is mentioned on no. 10 with one game (without a doubt Settlers Online), Ubisoft's 7 games on no. 11 also most certainly contain titles which are fully or co-developed by Blue Byte (Ubisoft's Anno, Panzer General. Might & Magic and Silent Hunter Online are all at least co-developed by BB) and I think at least no. 15 is developed by a German company as well.
